1. Field of the Invention
The present invention relates to the field of flow control. More specifically, the invention relates to a device and method for controlling the flow of fluids in a wellbore that, in one embodiment, provides for full tubing flow.
2. Background of the Related Art
The economic climate of the petroleum industry demands that oil companies continually improve their recovery systems to produce oil and gas more efficiently and economically from sources that are becoming increasingly difficult to exploit without increasing the cost to the consumer. One successful technique currently employed is the drilling of deviated wells, in which a number of horizontal wells are drilled from a central vertical borehole. In such wells, and in standard vertical wells, the well may pass through various hydrocarbon bearing zones or may extend through a single zone for a long distance. One method to increase the production of the well is to perforate the well in a number of different locations, either in the same hydrocarbon bearing zone or in different hydrocarbon bearing zones, and thereby increase the flow of hydrocarbons into the well.
One problem associated with producing from a well in this manner relates to the control of the flow of fluids from the well and to the management of the reservoir. For example, in a well producing from a number of separate zones (or from laterals in a multilateral well) in which one zone has a higher pressure than another zone, the higher pressure zone may produce into the lower pressure zone rather than to the surface. Similarly, in a horizontal well that extends through a single zone, perforations near the xe2x80x9cheelxe2x80x9d of the well, i.e., nearer the surface, may begin to produce water before those perforations near the xe2x80x9ctoexe2x80x9d of the well. The production of water near the heel reduces the overall production from the well. Likewise, gas coning may reduce the overall production from the well.
A manner of alleviating this problem is to insert a production tubing into the well, isolate each of the perforations or laterals with packers, and control the flow of fluids into or through the tubing. However, typical flow control systems provide for either on or off flow control with no provision for throttling of the flow. To fully control the reservoir and flow as needed to alleviate the above described problem, the flow is throttled. A number of devices have been developed or suggested to provide this throttling although each has certain drawbacks. Note that throttling may also be desired in wells having a single perforated production zone.
Specifically, the prior devices are typically either wireline retrievable valves, such as those that are set within the side pocket of a mandrel, or tubing retrievable valves that are affixed to the tubing string. The wireline retrievable valve has the advantage of retrieval and repair while providing effective flow control into the tubing without restricting the production bore. However, one drawback associated with the current wireline retrievable-type valves is that the valves cannot attain xe2x80x9cfull bore flow.xe2x80x9d An important consideration in developing a flow control system pertains to the size of the restriction created into the tubing. It is desirable to have full bore flow, meaning that the flow area through the valve when fully open should be at least as large as the flow area of the tubing so that the full capacity of the tubing may be used for production. Therefore, a system that provides full bore flow through the valve is desired.
One area of particular concern relating to downhole valves is the erosion caused by the combination of high flow rates, differential pressure and the properties of the fluids, which may contain solids, such as sand. Erosion of the tools results in premature failure of the valves.
A need remains for a flow control system that provides for full bore flow and for an efficient, reliable, erosion-resistant system that can withstand the caustic environment of a wellbore, including a deviated wellbore.
Certain aspects commensurate in scope with the originally claimed invention are set forth below. It should be understood that these aspects are presented merely to provide the reader with a brief summary of certain forms the invention might take and that these aspects are not intended to limit the scope of the invention. Indeed, the invention may encompass a variety of aspects that may not be set forth below.
According to one aspect of the present invention, a valve assembly for use in a well is featured. The valve assembly comprises a valve body, a valve choke, and a sealing member. The valve body has a flow port. The valve choke has at least one orifice. The valve body and valve choke surround a hollow interior. The sealing member is located between the valve body and the valve choke. The valve assembly is operable to provide fluid flow through the flow port and at least one orifice to the hollow interior by positioning the at least one orifice on a first side of a seal formed by the sealing member. Additionally, the valve assembly is operable to prevent fluid communication between the flow port and the at least one orifice by positioning the at least one orifice on a second side of the seal.
According to another aspect of the present invention, a valve assembly for controlling the intake of wellbore fluids is featured. The valve assembly comprises a housing and a choke. The outer housing has a fluid inlet. The choke has an outer surface and a plurality of orifices through the outer surface. Each of the plurality of orifices is separated by a solid portion of the choke outer surface. The valve assembly is operable to position the seal relative to the choke so that the seal engages the choke a solid surface portion, rather than an orifice.
According to another aspect of the present invention, a method of operating a valve assembly is featured. The method comprises deploying a valve assembly having a choke with a plurality of holes through the choke and a sealing member into a wellbore. The method also comprises operating the valve assembly to move the choke incrementally between a plurality of positions to control fluid flow into the valve assembly from the wellbore. At each of the plurality of positions the sealing member is positioned against a solid surface portion of the choke.
According to another aspect of the present invention, a system for controlling fluid flow from a wellbore is featured. The system comprises a valve assembly disposed in the wellbore and tubing to convey fluid from the wellbore to the surface. The valve assembly comprises a valve body having a flow port, a valve choke having an orifice, and a seal disposed between the valve body and the valve choke. The valve assembly also comprises a drive mechanism. The drive mechanism is operable to position the valve choke relative to the seal. Additionally, the drive mechanism is operable to position the valve choke to a first position relative to the seal so that the orifice is in complete fluid communication with the wellbore and the hollow interior.
According to another aspect of the present invention, a protective device for an orifice within a wellbore valve assembly is featured. The protective device comprises an insert having a fluid flow path therethrough. The insert is sized for insertion into the orifice. Furthermore, the insert comprises an erosion resistant material.
According to another aspect of the present invention, a deformable sealing device for use in forming a seal between a valve choke and a valve body is featured. The deformable sealing device comprises a seal ring configured to selectively form a seal between the valve choke and the valve body. The seal comprises an erosion resistant material.